Picking out UPS Backup Battery Solution...

I'm struggling with the math a bit to figure out how much backup power I need. It's for a restaurant and they requested 40 minutes to print receipts and have guests pay bills. I'm not sure that this is neither reasonable or wise. It is probably going to be way too expensive to maintain and swap batteries and if a business is out of power for more than 40 minutes, they probably should be evacuating.

Either way, I have two network racks in this building with 8 PoE Switches, 90 PoE cameras, 30+ PoE WAPs, 15 PoE phones. Pretty even split between racks. I've looked up the max wattage on the switches and I'm looking at about 1500W per rack, even though it may be less than that because we don't have PoE on every port and that is the switches max.

Then I have an area with 2 server computers. Then the MPOE. And then I need a few POS terminals up....